Introduction

The Capacitive Soil Moisture Sensor measures water content in soil by detecting changes in capacitance rather than resistance (like traditional probes). This makes it resistant to corrosion and provides more accurate, long-lasting measurements for smart gardening and agricultural systems.

Key Features

Technical Specifications

Pin Configuration

Wire Color	Function	Arduino Connection
Red	VCC	3.3V/5V
Black	GND	GND
Yellow	OUT	Analog Pin (A0-A5)

Wiring with Arduino

// Basic Connection:
// Red   → Arduino 5V
// Black → Arduino GND
// Yellow → Arduino A0

Basic Reading Example

const int sensorPin = A0;

void setup() {
  Serial.begin(9600);
}

void loop() {
  int sensorValue = analogRead(sensorPin);
  int moisturePercent = map(sensorValue, 0, 1023, 0, 100);
  
  Serial.print("Raw Value: ");
  Serial.print(sensorValue);
  Serial.print(" | Moisture: ");
  Serial.print(moisturePercent);
  Serial.println("%");
  
  delay(1000);
}

Calibration Procedure

1. Dry Calibration: Measure sensor in completely dry soil (record value as 0%)
2. Wet Calibration: Measure sensor submerged in water (record value as 100%)
3. Update Code: Adjust map() function with your calibration values

// After calibration:
int moisturePercent = map(sensorValue, dryValue, wetValue, 0, 100);

Advanced Usage

if(moisturePercent < 30) {
  digitalWrite(relayPin, HIGH);
  delay(2000);
  digitalWrite(relayPin, LOW);
}

#include <SD.h>
File dataFile = SD.open("datalog.txt", FILE_WRITE);
dataFile.println(moisturePercent);
dataFile.close();

#include <ESP8266WiFi.h>
WiFiClient client;
client.print("GET /update?field1=");
client.print(moisturePercent);

Troubleshooting